Cavitary pulmonary cryptococcosis with an Aspergillus fungus ball.

We herein present the case of a 64-year-old immunocompetent man with a diagnosis of pulmonary cryptococcosis who presented with cavitary nodules, one of which contained a fungus ball, on chest CT. The coincidence of cavitary cryptococcosis and an Aspergillus fungus ball was histologically confirmed on a thoracoscopic lung biopsy. Encapsulated round-to-oval yeasts (Cryptococcus) were observed throughout the entire specimen, including the cavity, cavity wall and lung parenchyma. In contrast, filamentous fungi (Aspergillus) were noted within the cavity only. The probable mechanism of this rare manifestation is that the Cryptococcus formed cavities, after which an Aspergillus fungus ball developed within one cavity.